The present invention resides generally in the field of devices and methods useful for treating fistulae, and in a particular aspect relates to the treatment of an anorectal fistula by filling its primary opening with a remodelable graft material.
As further background, a variety of fistulae can occur in humans and can occur for a variety of reasons, such as a congenital defect, inflammatory bowel disease, such as Chron's disease, irradiation, trauma, such as childbirth, or as a side effect from a surgical procedure. Fistulae that can occur in humans can include, for example, urethro-vaginal fistulae, vesico-vaginal fistulae, tracheo-esophageal fistulae, gastro-cutaneous fistulae, and any number of anorectal fistulae, such as recto-vaginal fistula, recto-vesical fistulae, recto-urethral fistulae, or recto-prostatic fistulae.
Anorectal fistulae can result from infection in the anal glands, which are located around the circumference of the distal anal canal which forms the dentate line. Approximately twenty to thirty such glands are found in humans. Infection in an anal gland usually results in an abscess, and the abscess can then track through or around the sphincter muscles into the perianal skin, where it can drain, either autonomously or via a surgical procedure. The tract that can result from the abscess is known as a fistula. The inner opening of the fistula, usually located at the dentate line, is known as the primary opening. The outer or external fistula opening is usually located in the perianal skin and is known as the secondary opening.
Anorectal fistulae can form a variety of pathways through the perianal tissue. For example, a fistula may take a take a “straight line” path from the primary to the secondary opening. This type of fistula is known as a simple fistula. Alternatively, a fistula may form multiple tracts ramifying from the primary opening and having multiple secondary openings. This type of fistula is known as a complex fistula.
The anatomic pathway that a fistula occupies can be classified according to its relationship to the anal sphincter muscles. The anal sphincter includes two concentric bands of muscle, the inner or internal sphincter muscle and the outer or external anal sphincter muscle. A fistula which passes between the inner and outer sphincter muscles is known as an inter-sphincteric fistula. A fistula that passes through both the internal and external sphincter muscles is known as a trans-sphincteric fistula, and a fistula that passes above both sphincter muscles is known as a supra-sphincteric fistula. A fistula that results from Crohn's disease usually ignores these anatomic planes, and is known as an extra-anatomic fistula.
Many complex fistulae consist of multiple tracts, some blind-ending and others leading to multiple secondary openings. One of the most common complex types of fistulae is known as a horseshoe fistula. In a horseshoe fistula, the infection can start in an anal gland (the primary opening) at the 12 o'clock location, for example, (with the patient in the prone position). From this primary opening, multiple fistulae can pass bilaterally around the anal canal, in a circumferential manner. Multiple secondary openings can occur anywhere around the periphery of the anal canal, thereby resulting in a fistula tract with a characteristic horseshoe configuration.
One technique for treating a perianal fistula includes excising a fistula from anal tissue by making an incision adjacent the anus that sufficiently contacts the fistula to ensure complete removal of the fistula. This surgical procedure tends to sever the fibers of the anal sphincter, and may cause incontinence.
Another surgical treatment for fistulae, known as a fistulotomy, involves passing a fistula probe through the tract of a fistula in a blind manner, guiding the probe primarily with only tactile sensation and experience. After passing the probe through the fistula tract, the overlying tissue can then be surgically divided and the fistula tract can then be allowed to heal. Because a variable amount of sphincter muscle can be divided during a fistulotomy, a fistulotomy may result in impaired sphincter control, and even frank incontinence.
Yet another technique for treating fistulae involves “coring-out” the tracts of one or more fistula, such as is described in U.S. Pat. Nos. 5,628,762 and 5,643,305. Unfortunately, however, these “coring-out” of procedures tend to make a fistula wider and more difficult to close. Additionally, the treatment of fistulae with surgical techniques, can lead to other potential complications, such as incontinence and multiple complex fistula formation.
In an alternative procedure, a fistula tract may be treated by inserting a seton, or a narrow diameter rubber drain through the fistula tract. The seton can be passed through the fistula tract and tied in a loop around the contained tissue and left for several weeks or months, thereby draining any infection from the area. This procedure is usually performed to mature the fistula tract prior to the performance of a more definitive closure procedure.
More recently, treatment methods have evolved which can include the injection of a sclerosant or a sealant, such as a collagen or fibrin glue, into a fistula tract in order to block and/or close the fistula. Glues used in these procedures can be very viscous and can clog the narrow channels of instruments used to deliver the sealants into the tract. The closure of a fistula with a sealant is usually performed as a two-stage procedure. The first stage includes the placement of a seton in the fistula to drain any infection that is within the fistula tract. The second stage, which usually occurs several weeks after the seton is placed, includes the injection of a suitable glue or other sealant within the tract of the fistula.
In view of this background, the need remains for improved and alternative techniques, devices, and systems useful for treating fistulae, such as anorectal fistulae. Certain aspects of the present invention are addressed to these needs.